Silencer or muffler



Aug. 30, 1960 F. E. DEREMER SILENCER 0R MUFFLER 2 Sheets-Sheet l Filed Aug. l, 1956 .Z'Nszz NT DH.: T1: @ya EZZFRL'MER.

Aug. 30, 1960 F. E, DEREMER 2,950,777

SILENCER OR MUFFLER Filed Aug. l, 1956 Eff/5l@ 2 Sheets-Sheet 2 f f//2 "uw Z'NVENTDH z FL Uyl? .EDEHEMEA .AT TY'.

United States Patent SILENCER R MUFFLER Floyd E. Deremer, Livonia,

Manufacturing Company, poration of Michigan Mich., assignor to Oldberg Grand Haven, Mich., a cor- This invention relates to apparatus for attenuating sound waves of moving gas streams and more especially to silencers or muiilers for use with exhaust gas systems of internal combustion engines used in automotive vehicles.

Certain types of sound attenuating devices or mutiiers in use at the present time with exhaust systems of automotive vehicles include a chamber delined by a shell of generally oval configuration through which the exhaust gas stream of an engine is directed, the interior construction of the sound attenuating device or muler incorporating tubular gas passages and resonating or sound attenuating chambers or compartments for the purpose of attenuating sound waves with a minimum of back pressure of the gas stream. In the type `of muiiler embody ing an oval shell, the gas passage tubes are generally arranged whereby the exhaust gases move transversely and longitudinally interiorly of the muffler shell and are discharged through a suitable o-utlet tube.

A muffler shell or casing of oval or ellipsoidal-shaped cross section is preferred especially as the trend of vehicle design is a lowering of the center of gravity of the vehicle and hence the vehicle oor with the muiiler disposed beneath the floor.

The oval muiiler provides a configuration adapted to obtain a maximum clearance between the bottom of the mulier shell and the roadway. In oval or ellipsoidalshaped mumer constructions heretofore used, the inlet and outlet members or tubes of the muffler have been disposed in the plane of the principal axis of the ellipsoidal coniiguration.

The vehicle frame or chassis construction embodies cross members which present difficulties in mounting or disposing the muiiler close to the vehicle iloor. The present invention includes a novel orientation of elements ywithin the mutiler andthe inlet or outlet pipes or tubes arranged for positioning `of the muffler nearer to the licor of the body than has heretofore been possible. Due to the proximity of the mutller to the vehicle floor, the heat from the exhaust gases in conventional muiiler constructions would be readily transferred to the floor. This difficulty is avoided in the present invention through the provision of novel means in the muiiler construction minimizing heat transfer transversely of the muffler.

An object of the invention relates to a novel construe-j tion of intermediate shell `or balile means in a muler construction which lfacilitates positioning the outlet tube' ol-center of the longer or principal axis of the oval or ellipsoidal main shell whereby interference with frame cross members of the vehicle is avoided.

Another object of the invention is the provision of an intermediate shell or baille construction which may be fabricated of al single sheet of metal and disposed between opposed walls of the muiiler shell in such a manner as to isolate the chamber adjacent a region of the muffler outlet tube and permit the mutlier to be positioned close to the vehicle lloor.

ICC

Another object of the invention is the provision of a sound attenuating or muler construction for use with a gas stream tformed with a double wall shell in which the walls are spaced to accommodate a sheet or layer of heat resistant material functioning both as a heat insulator and sound damping medium.

Another object of the invention is the provision of a muler casing or shell with spaced metallic walls adapted to accommodate a sheet of heat insulating material, the sheet being formed with openings through which the metal walls may be welded together and to elements or components contained within the casing whereby the metal parts are held in assembled relation and the heat insulating material restrained against movement by the metal at the welds.

Another object of the invention is the provision of a mutiler construction particularly for use with the exhaust gas stream `from an internal combustion engine which is of tubular shape and `of oval or generally ellipsoidal cross section, the arrangement embodying a plurality of gas passage tubes arranged in transverse overlapping relation wherein oneof the tubes at the overlapping region is isolated by means extending between opposed walls of the muilier shell or casing and wherein transversely overlapping regions of the gas passage tubes are formed with openings providing acoustic couplings yfor attenuating sound waves.

Funther objects and advantages are within the scope of this invention such as relate to the arrangement, operation and function of the related elements of the structure, to Various details of construction and to combinations of parts, elements per se, and to economies of manufacture and numerous other features as will be apparent from a consideration of the specification and drawing of a form of the invention, which may be preferred, in which:

Figure l is a longitudinal sectional view of a muiiler construction embodying a form of the invention, the section being taken on the line 1-1 of Figure 3;

Figure 2 is an end view of the construction shown in Figure 1;

Figure 3 is a transverse sectional View on an enlarged scale taken substantially on the line 3 3 of Figure l;

Figure 4 is a transverse sectional View taken substantially on the line 4-4 of Figure l;

Figure 5 is an isometric view of an intermediate shell or baille means forming a component of the mutiler construction of the invention;

Figure 6 is a fragmentary sectional view taken substantially on the line 6 6 of Figure l, and

Figure 7 is a plan View illustrating the conliguration or" a sheet or layer of heat resistant material forming a component of the muler construction.

While the muiller construction of the invention as illustrated in the drawings is of a type especially usable for attenuating the sound waves entrained in the exhaust gas streams from an internal combustion engine, it is to be understood that the principles of the invention may be utilized in any type of sound attenuator or silencer for attenuating or damping sound waves of a moving gas stream.

The form of the invention disclosed is inclusive of a casing, housing or shell of tubular construction having closed ends and equipped with gas passages and sound attenuating components disposed Within the casing or shell for attenuating or alleviating sound waves in an exhaust gas stream, the muffler being provided with one or more sound trap chambers and resonance tubes or chambers for attenuating sound Waves of particular lengths.

With particular reference to Figures 1 to 3 and 6 the shell or casing construction is of a double wall type comprising an inner wall 10 and an outer wall 12, each ofthe walls being preferably formed as an independent metal sheet. The sheets are spaced as particularly shown in Figure 3 and the meeting zones of the sheets are folded or bent upon themselves as at 14 Vforming a fluid tight seam or juncture extending lengthwise of the muflier construction.

The cross sectional configuration or shape of the muffler is preferably oval or generally ellipsoidal, but it is to be understood that the muiiier shell or casing may be of circular or polygonal shape in cross section if desired.

While the muflier shell construction is illustrated as formed of two sheets of metal, the shell may be fabricated of a single sheet of metal rolled upon itself in a spiral in which the convolutions are spaced and the end regions of the sheet overlapped and welded to provide a double wall.

In the illustrated embodiment, the outer metal layer or Wall 12 is formed with peripherally spaced indentations or depressions 16 providing inwardly projecting ridges which extend longitudinally of the muffler shell and provide longitudinally arranged chambers or confined zones 18. The shell or casing construction is provided with end heads or closures 20 and 22. The end regions of the shell walls 1t) and 12 are in engaging relations as shown at 24. The heads or end closures 20 or 22 are formed with peripheral ange portions 26 of U-shaped cross section which embrace the mating or engaging end regions of the shell walls and 12 in the manner particularly shown in Figure 1.

The chambers or confined zones 18, formed between adjacent depressed portions 16 of the outer wall, are individual in nature being substantially isolated from each other whereby there is little or no circulation of air through the chambers.

The chambers 18 are completely isolated from the interior of the muffler defined by the inner wall 10 and assist in reducing shell noise or vibration.

In certain installations of muffler construction it is desirable to provide a nonmetallic insulating medium to minimize radiation of heat from the exhaust gases and reduce sound transmission. In the form of the invention illustrated herein, a sheet or layer 30 of heat resistant material may be interposed between the inner and VVouter Walls of the shell. As hereinafter explained, the sheet of heat insulating material may extend throughout substantially the entire perimeter of the tubular portion of the mufiier or only over a partion of the area between the shell walls.

The end head 20 is formed with a circular flange 35 defining an opening arranged to accommodate a tubular fitting or tube 37 extending through the opening as shown in Figure 1. Telescoped with the tubular fitting 37 is a tube or tubular member 39 which with the fitting 37 forms a gas passage means through the end head 20 to the interior of the muffler. In the muffler illustrated, the fitting 37 serves as an inlet tube for the exhaust gases.

Spaced from the end head 20 is a header, transversely extending baffle member or wall 42 having a peripheral flange portion 43 configurated to engage the inner wall 10 throughout the periphery of the wall. The member 42 is formed with an opening defined by a flange 44,

through which extends the gas passage tube 39.

As particularly shown in Figure 1, the region of the gas passage tube 39 within the chamber 45 defined by the end head 20 and bafle or header 42, is provided with a comparatively large number of relatively small openings, holes or perforations 47. The openings 47 are preferably arranged in staggered relation as illustrated, the openings or perforations forming acoustic couplings with the chamber 45 whereby the latter serves as a sound trap for attenuating sound waves entrained in the gas stream.

A pair of transversely extending baffle walls or mem1 bers 49 and 50 are spaced lengthwise of the muffler shell as illustrated in Figure l. Each of the members 49 and 50 is formed with three openings. The openings receive respectively an end region of gas passage tube 39, an end region of a second gas passage tube S2 and a third tube 54, the tubes arranged as illustrated in Figure l.

The transversely overlapping regions of the tubes 39,

52 and 54 are provided respectively with a comparatively large number of small openings or perforations designated 56, 57 and 58. A

The gas passage tubes or means are arranged with other structural components so as to cause a substantial portion of the exhaust gases moving through the muler to be retroverted beforeA passing out of the muffler whereby to improve the sound attenuating characteristics of the apparatus. In the form of mufiier illustrated, the region of the outlet tube y52 provided with perforations 57 is isolated in a transverse direction from the tubes or gas passages 39 and 54 by a member or intermediate shell 60. The member 60 is particularly shown in Figures 3, 4 and 5 and is of generally tear-drop configuration in cross section having a circular cylindrical portion 62, convergingly arranged leg portions 64 and 65, and a connecting portion 66 joining the converging wall portions 64 and l65. The member 60 is preferably formed of a single metal sheet in which the end Zones of the sheet are overlapped as at 68 and the overlapping portionswelded or otherwise secured together as indicated at 69.

The transversely extending members or walls 49 and '50 are formed with shoulders 70 of the same contour as the member 60. The member 60 is arranged to be fitted over the shoulder portions 70 forming ya tear-drop or pearshaped chamber 72 surrounding the perforate region of the centrally disposed tube 52.

The member 60 forms an intermediate Shell dening the chamber 72 which avoids or prevents direct transverse passage of exhaust gases from the openings I56 in the tube 39 to the openings 58 in the gas passage tube 54.

The connecting portion 66 of member 69 is welded to the shell wall 10 as at 74 and the diametrically opposed region of the member 60 is likewise welded to the wall 10 as at 76. As particularly shown in Figure 3, the welds 74 join the depressed regions of two of the grooves or flutes in the outer shell 12, the inner shell 10 and the portion 66 at one side, and the welds 76 join the inner and outer walls and adjacent portion of member 60 together. By this arrangement the intermediate shell 60 is xedly secured to the shell construction.

The muiiier construction, in the embodiment illustrated, includes resonance chambers and tuning or attenuating pipes for damping or attenuating sound Waves. Spacedly disposed within the inner shell 10 are transversely extending walls or bafes 79, and 81 as shown in Figure 1. These members together with the inner wall 10 and the end head 22 define or provide chambers 83, 34 and 85.

The member 79 is provided with a flanged opening in which is secured `a tuning or resonance tube 87. The members 79 and 80 are also formed with pairs of aligned openings defined or bounded by flanges through which extend the outlet tube 52 and a tuning or resonance tube 89. The transverse member or wall 81 is formed with an opening defined by a flange, the opening being larger than the diameter of the tube 52. 'I'he member 81 is also formed with an opening 92 defined by a flange, the opening being of larger diameter than the tuning tube 89.

As shown in Figure 3, the oval or ellipsoidal shaped cross section of the muffler provides for a minimum dimension in a vertical direction as viewed in Figure 3, the upper surface of the outer shell wall 12 being placed close to but slightly spaced from the vehicle =body oor. In order to accommodate cross members or'struts forming part of the vehicle chassis construction, the gas passage tube 52 is disposed centrally of the muffler construction and below the plane of the axes of the gas passage tubes 39 and 54.

Thus, as shown in Figure 3, the axes of thetubes 39 and 54 are arranged in a plane AA at the principal axis ofthe ellipsoidal configuration of the muier. The axis of the outlet tube 52 is spaced below the plane AA a dis tance indicated at B so as to position the outlet below cross members of the vehicle frame. Through this arrangement the muifler may be placed very close to the vehicle body floor and thereby obtain a maximum of road clearance for the muffler construction.

By reason of the position of the muffler construction close to the vehicle body door, it is desirable to provide means for minimizing or preventing the transfer or radiation of heat from the muffler to the vehicle iloor. To this end the mulfler construction of the invention is inclusive of a sheet or layer of heat resistant, nonmetallic material disposed between the inner shell wall and the outer 4wall 12.v This sheet or layer may be formed of such materials as asbestos, mineral ber such as glass fiber, rockwool or other material having the desired heat resistant and sound damping characteristics.

The annular openings 90 and 92 provide for the circulation of exhaust gases in chambers 84 and 85. In addition, the member 81 is provided with a plurality of openings 94, illustrated in broken lines in Figure 3, which also facilitate the transverse of gases through the chambers. The compartments -83 and 85 form resonance chambers which cooperate with the tuning tubes 87 and 89 to dampen or attenuate sound waves.

The end head 22 is provided with a flange 96 defining an opening in which is disposed a tubular fitting or member 98, the end region of the tube 52 being telescoped with the fitting 98 and vforming Itherewith an outlet passage for conducting exhaust gases out of the muffler. In the embodiment illustrated, the tubes 37 and 39 form the exhaust gas inlet passage and the tubes 52 and 98 form the exhaust gas outlet passage, but it is to be understood that in certain installations the flow of exhaust gas may be reversed wherein the tubes 52 and 98 may form the gas inlet.

One of the factors affecting muiier installations in the present designs of vehicles is a trend to lowering the vehicle chassis and body to improve stability through a lowered center of gravity. There is, however, a minimum road clearance which must be maintained. The muffler construction is disposed beneath the body floor usually between or adjacent longitudinally extending chassis frame members.

The longitudinally extending frame members are, of necessity, joined by transversely extending brace members or struts which present installation difficulties or interference with a tail pipe 100 connected with the end region of the exhaust gas outlet tube 98. It is imperative to dispose the mutlier as close to the vehicle body floor as possible in order to provide the necessary road clearance.

Figure 7 is illustrative of the configuration of a sheet of asbestos or glass fiber 105 which, in assembled relation between the muffler shell walls 10 and 12 occupies the position shown in Figure 3. In this position, the heat resistant material 10S is completely sealed or isolated within the space between the inner and outer shell walls so that it is not affected by moisture and weather conditions. By employing material such as asbestos or glass fibers for the insulating layer, the layer has a certain degree of resilience, and being in contact with portions of both walls of the shell, the layer minimizes or eliminates so-called shell noise or shell vibration.

A feature of the present invention resides in configurating the sheet or layer of heat resistant material so as to facilitate welding the metal components of the mulfler together after the sheet or layer is assembled between the shell walls. The sheet is provided with slots or openings to provide for metal-to-metal contact ybetween the shell walls 10 and 12 at the zones or regions where it is desired to weld the transversely extending partitions, baiies or headers 42, 49, 50, 79, 80 and 81 and the intermediate shell 60 to the shell walls.

By way of example, the transverse slots or openings ,6 108 provide spaces for welding the walls or partitions 42 and the pairs of slots 110, 111 and 112 provide openings respectively through which the shell walls are welded together and to the transverse members 79, and 81. The groups of comparatively short slots 115 provide spaces through which the transversely extending members 49 and 50` are spot welded to the shell construction.

The longitudinally extending slots 118 provide spaces to Vfacilitate the welds 74 and 76 joining the intermediate shell 60 to the inner wall 10 of the muiher construction. rThrough the provision of closed slots in the sheet to accommodate the welds, the sheet as a single component may be readily assembled between the walls.

Through this medium and means of assembling heat resistant material between the muffler shells, the cost of assembly is greatly reduced as the heat resistant material is fabricated as a single element substantially surrounding the inner shell wall 10 and capable of installation with a minimum of labor.

In certain installations it may vbe desirable to provide heat insulation only at the upper region between the shell walls in the Zone nearest to the vehicle body floor. Where such construction is desirable, one half of the sheet may be used by severing the sheet along the median line CC shown in Figure 7.

In the operation of the muffler construction in the form illustrated, the tubular fitting 37 is connected with the engine exhaust gas manifold by suitable means (not shown), the exhaust gases moving into the mufiler through the gas passage provided by the tubes or members 37 and 39. Some of the sound waves of the gas stream are attenuated in the sound trap chamber 45 through the acoustic couplings or openings 47. By reason of the presence of the intermediate shell or battle member Gti forming the chamber 72, the major amount of exhaust gases traverses the space or passage 53 existent between the transverse walls 50 and `79 as the gases cannot flow from perforations 56 directly to perforations 57 or 5S, the gas passing in a left-hand or retroverted direction through the gas passage tube 54 thence through the transverse passage or chamber 46 existent between the transversely extending walls 42 and `49 into the gas outlet passage provided by the tube 52.

Through the provision of the intermediate shell 60, the major amount of exhaust gases entering the muffler is caused to move in parallel but opposite directions, thus effectively lengthening the path of travel or traverse of the gases through the muffler so that effective sound attenuation may be obtained throughout a wide range of sound wave lengths.

While the outer shell wall has been shown as embodying flutes or linear depressions, it is to be understood that both walls 10 and 12 may be smooth or ungrooved, or the flutes or depressions may be formed in the inner wall 1t) without departing from the spirit and scope of the invention.

t is apparent that, within the scope of the invention, modifications and different arrangements may be made other than is herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

I claim:

l. A muffler for use with the exhaust system of an internal combustion engine including a tubular shell, closures secured to the ends of the shell, gas passage tubes in said shell forming exhaust gas inlet and outlet means, a third gas passage tube in said casing in transverse overlapping relation with said gas inlet and outlet tubes, the intermediate tube of said three tubes being disposed with its axis offset from a plane passing through the axes of the other tubes, an intermediate imperforate casing surrounding the oset tube at its region of transverse overlap with the other tubes, said intermediate casing being one piece of sheet metal formed with a generally semicircular portion and convergingly arranged wall sections,

the semi-circular portion being welded to an inner surface f the tubular shell, said Wall sections terminating in flanges disposed adjacent and secured to an inner surface of the tubular casing, baie members in said shell spaced from the end closures and forming end Walls for the intermediate casing, the Wall of the offset tube Within the intermediate casing being provided With a plurality of comparatively small openings forming acoustic couplings with the interior of the chamber delinedby the intermediate casing and the baiile member.

2. A muffler for use With a gas stream including an elongated tubular shell of generally oval shape inv crosssection, closures secured to the ends of the shell, gas passage tubes in said shell having portions extending through openings in said closures respectively forming gas inlet and outlet means for the shell, a third gas passage tube in said shell, said gas passage tubes having portions in transversely spaced overlapping relation Within the shell, the intermediate tube of said three tubes being disposed with its axis offset from a plane passing through the axes of the other tubes, an intermediate imperforate tubular casing surrounding the intermediate tube at its region of transverse overlap with the other tubes, said intermediate casing being of a single sheet of metal formed with a generally semi-circular portion joined with convergingly arranged Wall portions and the end regions of the Wall portions extending transversely in overlapping relation, the semicircular portion of said casing being welded to an inner surface of the tubular shell, the overlapping end regions of the convergingly arranged Walls being Welded to an inner surface of the tubular shell substantially diametrically opposite to the region of the Weld of the semi-circular portion With the tubular casing, baille members in said tubular shell spaced from the end closures and forming end walls for the intermediate casing, the regions of each of the gas passage tubes in transverse overlapping relation being provided With a plurality of comparatively small openings in the walls thereof forming acoustic couplings with the regions surrounding the tubes between the balile members.

3. A muler for use with the exhaust system of an internal combustion engine including a double Wall shell of generally oval shape in cross section, said shell walls being in spaced relation throughout the major area thereof, closures disposed at the end zones of the main shell and secured thereto gas inlet and outlet tubes respectively disposed in openings in said end closures, said inlet and outlet tubes having portions in transverse overlapping relation, a third tube spaced from the inlet and outlet tubes, one of said tubes being offset from a plane through the axes of the other tubes, an intermediate tubular member formed of one piece of sheet metal and of generally teardrop configuration in cross section surrounding the offset tube at its overlapping region with the other tubes, the end regionsof the sheet of metal forming the intermediate member being in overlapping relation, a layer of nonmetallic mineral material disposed between the shell walls and having an opening adjacent the Zone of engagement of the overlapping portions of the intermediate member with the inner Wall of the shell, said walls and adjacent overlapping portions of the inten mediate member being Welded together, and transversely extending baille members disposed at the respective ends of the intermediate tubular member.

4. A muiiler for use with the exhaust system of an internal combustion engine including a double Wall main shell of tubular configuration, said shell Walls being in spaced relationv throughout the major area thereof, closures disposed at the end zones of the main shell, gas inlet and outlet tubes respectively disposed in openings in said end closures, said inlet and outlet tubes being in transverse overlapping relation, a third tube spaced from the inlet and outlet tubes and disposed adjacent the overlapping regions thereof, the intermediate tube of the said three tubes being disposed With its axis oiset from a lplane passing through the axes of the other tubes, an

intermediate shell of generally teardrop conliguration in cross-section surrounding the intermediate tube at its region of transverse overlap with the other tubes, said intermediate shell being formed of one piece of sheet metal, the end regions of the sheet metal forming the teardrop conguration being in overlapping relation and the overlapping regions disposed adjacent the inner Wall surface of the main shell, a layer of asbestos between said shell walls andJhaving an opening formed therein adjacent the zone of overlap of the end regions of the intermediate tubular shell, the said main shell Walls and the overlapping end regions of the metal sheet forming the intermediate Ashell being welded togetherl in the region of the opening formed in the asbestos layer.

References Cited in the le of this patent UNTTED STATES PATENTS 932,723 vSmith Aug. 31, 1909 1,931,736 =Noblitt et al Oct. 24, 1933 2,018,084 Oldberg Oct. 22, 1935 2,022,899 Oldberg Dec. 3, 1935 2,038,309 Oldberg Apr. 21, 1936 `2,111,537 Noblitt et al Mar. 15, 1938 2,161,155 Gettelman June 6, 1939 2,193,791 Hollerith et al. Mar. 19, 1940 2,652,128 Cary Sept. 15, 1953 2,656,005 Cary oet. 20, 1953 2,661,073

-Deremer Dec. 1, 1953 

